A satellite radiowave receiving device includes: a receiving unit which receives a radiowave signal; a conversion unit which converts the radiowave signal into digital data; a detection/arithmetic operation unit which detects the satellite signal; a capturing unit which searches a reception frequency; a setting unit which sets a second bit number, and the number of parallel processing in which the predetermined arithmetic operation can be executed in parallel; and a specifying unit which specifies the reception frequency of the satellite signal, and the detection/arithmetic operation unit executes the predetermined arithmetic operation in parallel for the input signal data related to reception frequencies of which number is equal to or less than a predetermined number of maximum parallel processing, and the number of parallel processing is determined so that a total bit number is equal to or less than the maximum bit number/the number of maximum processing.